<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8" />
    <title>粒子随心动画</title>
    <script src="http://cdn.sucai8.cn/cdn/jquery/jquery-1.10.2.js"></script>
    <style>
        body {
            overflow: hidden;
            margin: 0;
        }
        
        .twitter:hover a {
            transform: rotate(-45deg) scale(1.05);
        }
        
        .twitter:hover i {
            color: #21c2ff;
        }
        
        .twitter a {
            bottom: -40px;
            right: -75px;
            transform: rotate(-45deg);
        }
        
        .twitter i {
            bottom: 7px;
            right: 7px;
            color: #00aced;
        }
        
        .social-icon a {
            position: absolute;
            background: white;
            color: white;
            box-shadow: -1px -1px 20px 0px rgba(0, 0, 0, 0.3);
            display: inline-block;
            width: 150px;
            height: 80px;
            transform-origin: 50% 50%;
            transition: 0.15s ease-out;
        }
        
        .social-icon i {
            position: absolute;
            pointer-events: none;
            z-index: 1000;
            transition: 0.15s ease-out;
        }
        
        .youtube:hover a {
            transform: rotate(45deg) scale(1.05);
        }
        
        .youtube:hover i {
            color: #ec4c44;
        }
        
        .youtube a {
            bottom: -40px;
            left: -75px;
            transform: rotate(45deg);
        }
        
        .youtube i {
            bottom: 7px;
            left: 7px;
            color: #e62117;
        }
    </style>
</head>

<body>
    <canvas></canvas>

    <script>
        "use strict";

        // Initial Setup
        var canvas = document.querySelector("canvas");
        var c = canvas.getContext("2d");

        canvas.width = innerWidth;
        canvas.height = innerHeight;

        // Variables
        var mouse = {
            x: innerWidth / 2,
            y: innerHeight / 2 - 80,
        };

        var colors = ["#00bdff", "#4d39ce", "#088eff"];

        // Event Listeners
        addEventListener("mousemove", function(event) {
            mouse.x = event.clientX;
            mouse.y = event.clientY;
        });

        addEventListener("resize", function() {
            canvas.width = innerWidth;
            canvas.height = innerHeight;

            init();
        });

        // Utility Functions
        function randomIntFromRange(min, max) {
            return Math.floor(Math.random() * (max - min + 1) + min);
        }

        function randomColor(colors) {
            return colors[Math.floor(Math.random() * colors.length)];
        }

        // Objects
        function Particle(x, y, radius, color) {
            var _this = this;

            var distance = randomIntFromRange(50, 120);
            this.x = x;
            this.y = y;
            this.radius = radius;
            this.color = color;
            this.radians = Math.random() * Math.PI * 2;
            this.velocity = 0.05;
            this.distanceFromCenter = {
                x: distance,
                y: distance,
            };
            this.prevDistanceFromCenter = {
                x: distance,
                y: distance,
            };
            this.lastMouse = {
                x: x,
                y: y
            };

            this.update = function() {
                var lastPoint = {
                    x: _this.x,
                    y: _this.y
                };
                // Move points over time
                _this.radians += _this.velocity;

                // Drag effect
                _this.lastMouse.x += (mouse.x - _this.lastMouse.x) * 0.05;
                _this.lastMouse.y += (mouse.y - _this.lastMouse.y) * 0.05;

                // Circular Motion
                _this.distanceFromCenter.x =
                    _this.prevDistanceFromCenter.x + Math.sin(_this.radians) * 100;
                _this.distanceFromCenter.y =
                    _this.prevDistanceFromCenter.x + Math.sin(_this.radians) * 100;

                _this.x =
                    _this.lastMouse.x +
                    Math.cos(_this.radians) * _this.distanceFromCenter.x;
                _this.y =
                    _this.lastMouse.y +
                    Math.sin(_this.radians) * _this.distanceFromCenter.y;

                _this.draw(lastPoint);
            };

            this.draw = function(lastPoint) {
                c.beginPath();
                c.strokeStyle = _this.color;
                c.lineWidth = _this.radius;
                c.moveTo(lastPoint.x, lastPoint.y);
                c.lineTo(_this.x, _this.y);
                c.stroke();
                c.closePath();
            };
        }

        // Implementation
        var particles = undefined;

        function init() {
            particles = [];

            for (var i = 0; i < 50; i++) {
                var radius = Math.random() * 2 + 1;
                particles.push(
                    new Particle(
                        canvas.width / 2,
                        canvas.height / 2,
                        radius,
                        randomColor(colors)
                    )
                );
            }
        }

        // Animation Loop
        function animate() {
            requestAnimationFrame(animate);
            c.fillStyle = "rgba(255, 255, 255, 0.05)";
            c.fillRect(0, 0, canvas.width, canvas.height);

            particles.forEach(function(particle) {
                particle.update();
            });
        }

        init();
        animate();
    </script>
</body>

</html>
